fix: add helpful output to admin console and dev proxy

[dpchamps]

problem

It's not immediately obvious from the dev-admin panel what processes are associated with what port. This can lead to some confusion, as outlined here

solution

Make the dev admin panel more transparent without being verbose, with things a dev will want/need to see at some point:

• Output pid alongside the process that's started / stopped, e.g.:
  • "your app server (PID: 59264) started"
  • "your app server (PID: 59264) exited code 0"
• Output tree to communicate proxy associations:
  • 

Additional Small change:

• Removed signal reporting when falsy:
  • ""your app server exited code 0 signal: null"

closes #1559